Pseudotorellia Florin from the Upper Jurassic–Lower Cretaceous of the Bureya Basin, Russian Far East

The leaves of the genus Pseudotorellia from the Upper Jurassic–Lower Cretaceous of the Bureya Basin (Russian Far East) have been revised. The similarity of Pseudotorellia angustifolia Doludenko and P. longifolia Doludenko in the morphology and epidermal characters suggests that P. longifolia is a synonym of P. angustifolia. Leaves of this genus from the Bureya Basin previously assigned to P. ensiformis (Heer) Doludenko according to both morphological and epidermal characters are described as a new species P. doludenkoae sp. nov., since the type specimens of P.ensiformis from the Irkutsk Basin do not have preserved cuticles and their leaf epidermal characters are unknown. The epidermal characters of leaves described previously as Pseudotorellia pulchella and P. crassifolia have been studied for the first time. Since these species have similar morphological and epidermal characters, they are described as P. crassifolia, and its emended diagnosis is provided. The well-defined epidermal characters of Pseudotorellia allow us to reliably assign even cuticle fragments and dispersed cuticles to a particular species. This indicates a large stratigraphic potential of the Pseudotorellia species for the intrabasin and interregional stratigraphy of continental deposits, especially when studying the core material and coals, where the preservation of plant remains usually does not allow describing their morphology. The revision of all known occurrences of Pseudotorellia angustifolia makes it possible to discuss the place and time of the first appearance of this species and its subsequent distribution in space and time. Apparently, this species appeared in the Early Jurassic of Eastern Siberia (Kansk Basin). In the Middle Jurassic, its range expanded both to the northwest (Tomsk oblast and Yamal-Nenets Autonomous Okrug), where this species was preserved until the Late Jurassic, and to the east (Irkutsk oblast, Khabarovsk krai (Bureya Basin)), where it survived until the Early Cretaceous.

FORMS OF ORE COMPONENT OCCURRENCE AND CONDITIONS OF THEIR TRANSPORT INTO BROWN COALS WITHIN THE ZONES OF CONTRAST JUNCTION BETWEEN SEDIMENTARY BASINS AND OROGENS USING THE ZEYA-BUREYA BASIN AND TURAN MASSIF AS AN EXAMPLE (FAR EAST, RUSSIA)

The conditions for the formation of Paleogene-Neogene metalliferous coals in a setting of tectonic movement intensification in the zone of junction between the Turan massif and Zeya-Bureya basin have been studied. The massif with the Selemdzha-Tomsk and Arkhara grabens separated by the Bureya horst and bounded by the systems of northeastern strike-slip faults was found to have a keyboard structure. The research showed that the most favorable conditions for the ore microcomponent accumulation in coals through the erosion of the Late Cretaceous ore-bearing chemical residue were within the submerged blocks of the massif. The paleodrainage system carrying microcomponents drained the grabens and the associated sedimentary sub-basins of the Zeya-Bureya basin eastern margin. Ore components were transported mainly in solution and as solid clasts to the areas of coal accumulation as evidenced by the resemblance of the elementary composition of coals in the Zeya-Bureya basin and geochemical anomalies of the Turan massif.

The Late Cretaceous floras of the Zeya-Bureya Basin

A general characterization of the Late Cretaceous floras of the Zeya-Bureya Basin is provided based on floristic assemblages from Russia (Amur Region) and China (Heilongjiang Province). Four phases of floral evolution were revealed: the Turonian-Coniacian (the Sutara flora), the Santonian (the Yong’ancun and Middle Kundur floras), the Campanian (the Taipinglinchang and Late Kundur floras) and the late Maastrichtian (Bureya flora). This long paleofloral succession provides possibility for investigation of different trends in the evolution of the Late Cretaceous taxa, flora, and climate.

Distribution of Cenozoic metalliferous coal deposits in Zeya-Bureya Sedimentary Basin (Eastern Siberia): Tectonic reconstruction and paleogeographic analysis

Distribution of noble metals, rare metals and rare earth elements in the Paleocene and Lower-Middle Miocene coals of Zeya-Bureya sedimentary basin was analyzed. Reconstruction of the basin formation in the Mesozoic and Cenozoic was performed with detailed paleogeographic analysis of the Cenozoic coal-bearing sequences from the position of geodynamic features of the adjacent regions development. Geological events at the turn of the Cretaceous and Paleogene are considered. Comprehensive analysis of the metal content in the basin frame carried out. We described conditions of migration and localization of trace elements. Given conditions arose mainly in the process of geodynamics developed on the northwestern flank of the Zeya-Bureya basin including the static orogens in the Paleocene — Miocene where the sedimentation was actively expanding. Microelements migration with capturing denudation plains occurred in stable processes of peat accumulation and localization of economically important components in streams associated with plains. Contrasting forms of conjugation in the flexure-uplift system and uneven localization of microelements are determined by high level of geodynamic activity on the south-eastern margin of Zeya-Bureya sedimentary basin. The presence of gold throughout the strata of the Paleocene and Lower-Middle Miocen coal-bearing sediments in the Sergeevskoe, Yerkovetskoe and Raychikhinskoe deposits is established. The Sergeevskoe deposit coals are enriched with Be, Sc, V, Ga, Rb, Nb, Ta, REE + Y.